Sophie Alexander

Sophie Alexander, Hemsworth Farm

Hemsworth Farm is a 410 ha organic farm working on a rotation of three years of grass and clover leys followed by spring wheat, winter oats and spring barley, and sometimes a bean crop. Cover crops are used over winter so none of our soils are left bare to help build soil fertility. The farm has now reintroduced stock to the farm as part of the rotations.

Field lab: Using compost teas on crops

This is the first large-scale arable trial into the effectiveness of compost teas the UK. The tea is made from water, compost and molasses, which have been aerated to multiply the micro-organisms, and sprayed onto crops. Year one results have been encouraging with one field seeing a 50% uplift in yield. Read more about this field lab here.

Why were you interested in compost teas?

We started at Hemsworth with very poor soils and have been looking for all ways to rebuild soil organic matter and improve soil microbiology.

I first read about compost tea a few years ago and was intrigued. Despite my interest in the topic, I think the first time I saw convincing results was in the film, Symphony of the Soils. This really caught my attention and I began to think about how we could roll this out over a few acres.

Although this technique has been used on football pitches and golf courses for years it’s never really caught on within agriculture. I know a little about root systems, and mycorrizal fungi but was intrigued by how compost teas might be able to improve these and other organisms present in the soils, and subsequently help our crops.

How has being part of the field lab benefited you?

The field lab group has been invaluable for many reasons. We all had soil sampling, including biological and chemistry samples, done before the trial, one of the things that was really beneficial. Being part of the group hasn’t just meant we can sample the compost teas at scale, but has allowed us access to the right scientific knowledge and sampling methods. Farm visits are really valuable. I always learn something from a farm visit.

I think I would find it quite hard to do these trials on my own; I find the guidance of the Organic Research Centre really helpful and they help keep us on track through accurate monitoring. You need more comparisons to find a better scientific outcome so linking with different farms around the country is essential. I like having a more scientific discipline and protocols in place too, otherwise it doesn’t stack up!

We’re doing it to improve the microbiology of the soil – so that the micro-organisms feeding on the roots of the plants, and then return nitrogen to the soil – which can be absorbed by the crop. It can also be applied as a foilial dressing to counteract the onset of disease.